Sharpening end mills on lathe

[I. Klemetti]

Well, I know it may not make sense to sharpen smallish endmills. But if we take it from the hobby point of view we don't have to think how productive we are. So instead of making a new engine one may get a kick out of sharpening a dull end mill.

I have a small Proxxon PD 230 lathe with some accessories. I wondered if I could utilize its precise slides and handwheels in sharpening endmills. So I made an adjustable attachement for a mini drill. The material is mild steel.

A dividing device with chuck is attached to the lathe ways. The end mill is attached in the chuck. So it is possible to turn the mill in precise 90 deg increments (four flute mill).

The lathe cross slide is locked. Compoud is turned so that its angle to the cross slide is 1.5 deg. This is the end mill concavity angle. I had to remove cross slide handwheel to be able to set the compound this way.

A heavy duty cutting disc is attached to mini drill and it is attached to the tool post, tilting 10 deg. at first. This is the end mill radial relief angle. The end mill is sharpened carefully with shallow radial cuts in 0.03-0.05 mm axial increments until the edges are sharp again. Then the mini drill is tilted 20 deg. for secondary relief angle and the process is repeated.

I took the above mentioned angles from a book and they are for 10 mm dia end mills.

The sharpened end mill is now sharper than ever. With this method it is not possible to sharpen against the edge. However I could not see any difference although the grinding wheel rotated the wrong way. The center part of the mill (some kind of relief grooves) is ground manually with the mini drill.

The last picture is a "before and after" shot.

-Ilkka-

 

[Tin Falcon]

Part of this hobby is finding what works and sharing . as long as it is safe please share.
thanks.
Tin

 

[Sleazey]

That is a great piece of thinking.

I have the PD 400, and the Proxxon IB/E rotary tool. I even have the lathe tool mount for the IB/E that Proxxon sells, but it doesn't allow any swiveling like your version does, but that's easy to fix.

I am bookmarking this thread.

Thanks for a really really clever idea!

 

[gus]

Hi Ilkka,

Good Idea. How come I never thought of it.
Though China EndMills are cheaper to buy here in Singapore and even more cheaper to buy in Southern China which I will going mid November.Us retirees have much time but less $$$$.Thought of building a dedicated Quon Grinder but had cold feet.My biggest end mill is 12mm.By now I have too many 6----12 mm cutters to reclaim.
PD 400 on my "want list" now moved to "need list ". Also plan to make some cutters too.

 

[gus]

That is a great piece of thinking.

I have the PD 400, and the Proxxon IB/E rotary tool. I even have the lathe tool mount for the IB/E that Proxxon sells, but it doesn't allow any swiveling like your version does, but that's easy to fix.

I am bookmarking this thread.

Thanks for a really really clever idea!

Hi Sleazy, SOS SOS SOS
How do bookmark this thread? Very useful to touch up small end mills and drills too.

 

[I. Klemetti]

Thanks guys! I'm glad you liked the idea.

...I even have the lathe tool mount for the IB/E that Proxxon sells, but it doesn't allow any swiveling like your version does...

Actually, I got the idea from that particular tool mount. I could even wedge it in the tool post for the relief angle, but I could not get it vertically right to get the disc centre at the end mill centre.

So I made my own adapter.

Originally, I was thinking about tilting the mini drill downwards and thus made the height adjustment to work downwards. However, it was easier to grind the nearest mill edge for better visibility. To get more upward adjustment I drilled and threaded extra attach holes near the edges of the clamp part. (The original single hole is at clamp centerline.) Still I have to mill the long hole upwards to be able to grind secondary relief angles more than 20 degrees.

BTW, I measured the relief angle settings with my phone inclinometer application. I calibrated the phone on the lathe ways and measured the angle at an axial surface of the mini drill.

-Ilkka-

 

[gus]

Hi Ikka,
I am now down to new 12mm x 4 fluke end mill and a very dull same size mill.
Just gave verbal order for 4 new end mills.Looks like I will eventually have a good size batch of dull cutters to just buying a Dremel to grind mills.

Happy New Year.

 

[OrangeAlpine]

What a clever idea. Finally, a good use for the Craftsman 109 lathe!